CA1207440A - Disc player with search noise suppression - Google Patents
Disc player with search noise suppressionInfo
- Publication number
- CA1207440A CA1207440A CA000428697A CA428697A CA1207440A CA 1207440 A CA1207440 A CA 1207440A CA 000428697 A CA000428697 A CA 000428697A CA 428697 A CA428697 A CA 428697A CA 1207440 A CA1207440 A CA 1207440A
- Authority
- CA
- Canada
- Prior art keywords
- program information
- data
- signal
- information data
- address data
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
- G11B5/09—Digital recording
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/005—Reproducing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
- G11B19/02—Control of operating function, e.g. switching from recording to reproducing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/18—Error detection or correction; Testing, e.g. of drop-outs
- G11B20/1866—Error detection or correction; Testing, e.g. of drop-outs by interleaving
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B21/00—Head arrangements not specific to the method of recording or reproducing
- G11B21/02—Driving or moving of heads
- G11B21/022—Programmed access in sequence to indexed parts of operating record carriers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
- Optical Recording Or Reproduction (AREA)
- Indexing, Searching, Synchronizing, And The Amount Of Synchronization Travel Of Record Carriers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A disc player, for reproducing program information from a disc on which the information is recorded as digital program information data accompanied by digital address data, comprises an optical reader for reading program information data and address data from the disc, such reader being selectively operable in a searching mode and in a playback mode, processing circuitry supplied with program information data to produce program information from the program information data, a detecting means that compares designated address data identifying desired program information with the reproduced address data in the output of the reader and system controlling means for controlling the reader to continue the searching mode until the reproduced address data match the designated address data, at which time the system controlling means operates the reader in its playback mode to read from the disc the program information data identified by the designated address data.
Noise-suppressing means substantially prevents the processing circuitry from producing program information from the program information data in the output of the reader operating in the searching mode. The clicking noises and other spurious sounds produced by prior art disc players from the program information data read during the searching mode are thus prevented from occuring before the production of desired program information from the disc.
A disc player, for reproducing program information from a disc on which the information is recorded as digital program information data accompanied by digital address data, comprises an optical reader for reading program information data and address data from the disc, such reader being selectively operable in a searching mode and in a playback mode, processing circuitry supplied with program information data to produce program information from the program information data, a detecting means that compares designated address data identifying desired program information with the reproduced address data in the output of the reader and system controlling means for controlling the reader to continue the searching mode until the reproduced address data match the designated address data, at which time the system controlling means operates the reader in its playback mode to read from the disc the program information data identified by the designated address data.
Noise-suppressing means substantially prevents the processing circuitry from producing program information from the program information data in the output of the reader operating in the searching mode. The clicking noises and other spurious sounds produced by prior art disc players from the program information data read during the searching mode are thus prevented from occuring before the production of desired program information from the disc.
Description
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S017~9 BAC~GROUN~ OF TIIE INVENTION
Field of the Invention -This invention relates to a method and an apparatus for reproducing program information from a medium in which noise generated by searching for predetermined program information on the medium is suppressed and, more particularly, to a disc player incorporating such a method and apparatus.
Description of the Prior Art In a ~nown recording system a rotatable disc-shaped record medium is used to record digital data representing an audio signal. The digital data are arranged in data blocks that include program information data representing the audio signal, data for error correction, synchronous data and address data. A
disc player is used to reproduce the audio signal from the digital data recorded on the disc. With such a system, very high fidelity reproduction of the audio signal can be obtained.
However, errors in the program information data read by the disc player can affect the reproduced audio signal.
Generally, digital data recorded in any medium inevitably contain data errors caused in the recording process. Such data errors appear infrequently enough that a high Lidelity audio signal can still be obtained Lrom the program information data using error correction techni~ues. Fingerprirts and scratches on the surface or the disc also can cause data errors because they prevent accuxate reading or the program information data recorded on the disc.
Accordingly, recording and reproducing systems using digital data on a disc incorporate a cross-interleave error correction technique for correcting errors that appear in the , , ., -~z~
program inrormation data read from the disc. In recording datausiny a cross-interleave error correction technique, a first error correcting code for a first code arrangement stage and a second error correcting code fox a second code arrangement stage are provided, and then an interleave is carried out between the first and second stages. Using a Reed-Solomon code for the error correcting codes and the interleave technique allows very accurate error correction of the reproduced program information data. However, the corresponding processing circuitry in the disc player for using that error correcting technique requires a finite time, called a de-interleave delay, to convert into program information the program information data read from the disc. That delay causes a problem.
The address data recorded on the disc with the program information data make it possible to reproduce selectively any desired portion of the program information data. The reading device in the disc player is made operative in a searching mode and address data ccnt2ined in the output from _he ~eadin~ deYJice is compared with designated address data associated with the location on the disc of the desired program information. The reading device is operated in the searching mode until the reproduced address data coincide with the designated address data. mhe reading device is then made operative in a playback mode to read the program information data at the location on the disc where the address data match the designated address data.
The output of the reading device in the séarching mode also intermittently contains small amounts of program information data, which is supplied to the processing circuitry and converted into an audio signal after the de-interleave delay time. The audio signal thus obtained appears as a clicking noise or other undesired sound before the selected program information data is reached and converted into the desired program information. The de-interleave delay prevents suppression of that noise merely by preventing conversion of program information data into program information while the reading device is in the searching mode hecause the program information data in the output of the reading device can still be undergoing conversion after the searching mode is terminated.
OBJECTS AND SUI~MAR~ OF THE INV~NTION
~ ccordingly, it is an object of the present invention to provide a method and an apparatus for reproducing program information from a medium that avoids the above described problem encountered in prior art apparatus.
It i5 another object of the present invention to provide for reproducing digital program information data from a disc and suppressing the production of noise caused by operation in a searching mode.
According to an aspect of the present invention r program information is reproduced from a medium containing a plurality of blocks of program information data, each block including address data. During a searching mode, an output is provided containing program informa!ion data and addrcss data used in locating predetermined address data~ The predetermined address data is detected in the output and~ in response to such detection, the medium is read in a playback mode to provide an output comprising program information data for conversion into program information. The conversion into prog,am information of program information data provided during the searching mode is suppressed.
In accordance with one embodiment of the present invention, a clearing period is provided after the playback mode begins when the output contains su~stantially no program information data and the conversion of program information data into program information is suppressed for a predetermined muting time after the predetermined address data is detected, the clearing period being at least as long as the muting time.
In accordance with another embodiment of the present invention, a silent-data slgnal corresponding to program information data containing substantially no program information for converC,ion into program information is generated during the searching mode.
The above and other objects, features and advantages of the present invention will be apparent from the following detailed description tal~en in con~unction with the accompanying drawings.
BRIEF ~ESCRIPTION OF _HE DRAWI~IGS
.
FIG. 1 is an illustration of one type of searching operation that causes the production of undesired audio signals in prior art disc players;
FIG. 2 is an illustration of another type of searching operation that causes the production of undesired audio signals in prior art disc players;
FIG. 3 is a schematic block diagram showing a disc player incorporating a first embodiment of the present invention;
FIG. 4 is a schematic bloc~ diagram showing in detail the operation of the decoding circuitry used in the disc player o F the present lnvention;
FIG. 5 is an illustration of the searching operation performed by the embodiment of the present invention shown in FIG. 3, and FIG. 6 is a schematic block diagram showing a disc player incorporating another embodiment of the present invention.
DETAIL~D DESCRIPTION OF ILLUSTRATIVE E~'~ODIMENTS
FIG. 1 depicts a searching operation that illustrates the problem with spurious search noise encountered in prior art disc players. Assume that the reproduction of program information on a disc is to commence at ~he beginning of a recorded area N in a record track T on the disc. The disc player reading device, operated in its searching mode, moves along the path p in FIG. 1. In doing so the reading device repeatedly goes over areas containing program information data, such as the recorded area N, and areas where no program information data are recorded, such as the area e located between the recorded area N
and a recorded area N-l. The reading device repeatedly moves across the disc until it reaches a position p~ that corresponds to the beginning of the recorded area N.
When the address data provided at the beginning of the recorded area N are read out at the position Pl by the reading device and compared with the designated address data, the disc player determines that the reading device has reached the selected location. Consequently, the reading device is made operative in its playback mode and xeads the program information data in the area N from its beginning.
During the searching mode, and before the desired audio signal is produced from the program information data in the area N provided in the output of the reading device operating in its playbac~: mode, the reading device provides an output containing not only add~ess data but also program information data. During the searching mode, that unwanted program information data are supplied to the decoding circuitry and are converted into an audio signal after the de-interleave delay time (normally about 13.5 msec). The program information data, provided during the searching mode, appears as a clicking noise or other spurious audio signal.
FIG. 2 illustrates the same problem in a case in which the reproduction of program information data is .o be commmenced at a specific location Y~ within a recorded area N. The reading device, operating in its searching mode, moves on the record track T in the path p'. The reading uevice thus repeate~ly yoes over the location X while the amount of movement of the reading device is narrowed down, finally stopping at the location X.
When the address data at the specific location ~ within the recorded area N are read out at the position Pl' by the reading device and compared with the designated address data, the disc player determines that the reading device has reached the selected location. Consequently, t:he reading device is made operative in its playback mode and reads the program information data in the recorded area N, beginning at the location X.
As in the example discussed in ccnnection ~ith FIG. l, be~ore the desired audlo signal is obiained from the program inrormation data in the area ~, the pr~ram in~ormation data provided by the reading device operating in its searching mode are supplied to the decoding circuitry and are converted into an audio signal a~ter the de-interleave delay time. mhus, the same undesirable clicking noise or other spurious sound is p~oduced by the searching operation.
FIG. 3 shows a disc player according to one embodiment of the present invention that overcomes the problem associated with the searching operation depicted in FIG. 1. A disc 1 containing digital program information data accompanied with digital address data is rotated by a motor 2. mhe program information data and the address data recorded on the disc 1 are provided in the OtltpUt of a reading means, which in this embodiment comprises an optical head 3 that directs laser light toward the disc 1 and receives refiected laser l~ght from the disc 1. The reflected light is modulated in response to the data contained on the disc. A photodetector 4 converts the modulated reflected light into an electrical signal containing the program information data and the address data on the disc 1. The electrical signal from the photodetector 4 is shaped by a wa~reform shaping circuit 5 into a suitable digital signal. The digital signal thus obtained is supplied to a demodulator 6 that separates the program in~ormation data and the address data and provides ther;l irl the form o~ output program inrormation data S
and output address data L. The olltpUt address data L are supplied to a Lirst regis~er 7 to be held therein until they are read out in response 'o a control signal CN, supplied from a system controlling means 8, to one input terminal o~ a detecting means 9, as eY.plained below.
A keyboard 10 supplies a keying signal ~ to the system controliing means 8. The ke~rboard 10 comprises a designating means by which an operator can designate ~or playback predetermined program inrorr.ation by causin~ the syster, controlling means 8 to produce predetermined designated address data Lx locating the predetermined program inIormation on the disc in response to the ke~7ing signal ~. The predetermined address data Lx are supplied to a second register 11 to be held therein. The predetermined address data Lx are supplied from the second register 11 to the other input terminal of the detecting means 9. The detecting circuit 9 compares the output address data L with the predetermined a~dress data Lx, which at this time do not match. An operational signal P, obtained as a result of that comparison, is supplied to the system controlling means 8. A mode control signal Cc is supplied to the optical head 3 to establish the searching mode, in which the optical head 3 selectively operates for normal reproduction and for performing a fast-forward operation, a fast-reverse operation, a one-track-forward iumping operation and a one-track-backward iumping operation. The svstem controlling means 8 thus supplies a first mode control signal, effectively in response to the keying signal K, to establish the searching mode of the optical head 3. A timer 12 having a set time of, for example, 15 msec i~
triggered by a timer trigger signal TS provided by the system cont~-olling means ~ when the operational sigrlal P assumes the form of a match signal indicating that the output address data L
coincide with the predetermined address data Lx. In ~esponse to the trigger signal TS the timer 12 provides an over~low signal To to the system controlling means 8 when the set time from the receipt of the triggering signal TS has lapsed.
Meanwhile, the output program information data S from the demodulator 6 are supplied to decoding circuitry ~3 for performing error detection according to the cross-interleave technique, as described in more detail below. The decoded program information data obtained from the decodlng circuitry 13 are supplied to an interpolating circuit 14 in which detected errors are corrected by interpolation. The interpolatinq circuit 14 receives also a mutiny command signal CM and a muting release signal CM' from the system controlling means 8 for selectively actuating and deactuating muting means for suppressing the operation of the interpolating circuit 14 when actuated. The error-corrected, decoded program information data from the interpolating circuit 14 are supplied to a digital-to-analog converter 15 for producing an audio signal representing the progra~ information. The decoding circuitry 13, the interpolating circuit 14 and the digital-to-analog converter 15 thus comprise processing circuit means for eonverting program information da-ta into program information.
FIG. 4 shows in more detail the decoding circuitry 13.
The decoding circuitry 13 comprises a mutliplexer 16A, a first deeoder 16B, a de-interleaver 16C, whieh ineludes a plurality of delay deviees Dl, D2, ete., and a seeond deeoder 16D.
The output program infor~lation data S from the demodulator 6 are supplied to the multiple~er 16A. That data com~rise th~rt~7-twc worac, ~ncluding twenty-fou- audic sign21 data words Sl to S24, four first error~eorreeting words P
to P4 and f~ur seeond error-eorree,ing words Ql to Q4 in each da~a block. The output program information data S thus appear at the output ol the multiplexer 16A as parallel output data. These thirty-two words are supplied to the first decoder 16B. ~n the first decoder 16B~ the first error eorreetion for the data comprising the twenty-four audio signal data words S
to S2~ and the four first error eorreeting words Pl to P4 is carried out by using the four seeond error correcting words Ql to Q4. The first deeoder 16B thus derives data eomprising twenty-four audio signal data words S1' to S24' and rour first eorreeting words P~' to Pal all of which have been _~_ subjected to the first error correction process. At every individual word of the data of these twenty-eight words, a pointer (such as an additional bit) is added to indicate whether there is an error in the associated word or not.
The output data from the first decoder 16B are applied to the de-interleaver 16C which has the delay lines Dl to D28 with respective different delay amounts provided for the twenty eight transmission channels through which the twenty-eight words from the first decoder 16B are respectively transmitted.
With the delay lines Dl to D28, the twenty-eight wcrds from the first decoder 16B are delayed for de-interleaving and twenty-four audio signal data words Sl" to S24" and four first error correcting words Pl" to P4" are derived from the de-interleaver 16C. The sum of the dela~ amounts caused by the delay lines Dl to D28 (the de-interleave delay time) is typically about 13.5 msec. The output from the de-interleaver 16C is then supplied to the second decoder 16D. In the second decodQr 16~, the second error corrQction for the twerty-four audio signal data words Sl" to S24" is carried out by using the four first error correcting words Pl" to P4". The second decoder 16D thus derives twenty-four final audi~ signal data words Fl to F24 that have been subjected to the second error sorrection process and comprise decoded program information data~
At every individual word of these twenty-four words~ a pointer is added to indicate whether or not there is an error in the associated word.
The decoded program information data Fl to F2~ ~hus obtained are supplied to the interpolating circuit 14 for error correction by interpolation for the words having the pointer added thereto. Then, the error-corrected, decoded program 74~
information da-~a are supplied to the digital--o-analog converter 15. The digital-to-analog converter 15 converts the data from the interpolating circuit 14 into an audio signal representing the program information on the disc.
FIG. 5 illustrates the operation OL- the er~odirment of the present invention shown in FIG. 3 in relation to the reproduction o~ program information in a record trac~ ~ on a disc 1 commencing at the beginning of a recorded area N.
First, the keying signal ~, which will be used to eventuall~ position the optical head 3 at the beginning of the recorded area ~, is supplied to the system controlling means ~
from the keyboard 10. In response to the ~eying signal K, the system controlling means 8 provides the muting command signal CM to the interpolating circuit 14 so that the muting means in the interpolatin~ circuit 14 is actuated to block the provision of tne error-corrected, decoded program information data from being supplied to the digital-to-analog converter 15.
Simultaneously, the system controlling means 8 pro~ides the predetermined address data Lx, which corresponds to the address data at the beginning of the recorded area ~, to the second register 11. The mode con~rol signal Cc assumes its first form in which the optical hea~ 3 is placed in the searching mode. The predetermined address data Lx are supplied to the operational circuit 9 from the second register 11 and the output address data L obtained from the photodetector 4 are supplied to the~first register 7 and from there to the operational circuit 9. The operational circuit 9 compares the ou~put address data L with the predetermined address data Lx. When the output address data L
do noi r.latch the designated address data Lx, the mode control signal Cc continues to operate the optical hea~ 3 in its 4~
searching mode. During the searching mode, a comparison between the output address data L and the predetermined address data Lx is performed by the operational circuit 9 whenever address data on the disc 1 are read cut by the optical head 3. The first mode control signal Cc is varied in accordance with the operational signal P obtained in response to the result of that comparison in the opera.ional circuit 9. As a result, the optical head 3 is moved in an optimum fashion until the output address data L match the predetermined address data L . The optical head 3 in the searching mode thus moves in a path p as shown in FTG. 5. That is, in the searching mode, the optical head 3 repeatedly travels forward and backward over recorded areas and areas containing no data and the amount of overshoot of the selected location narrows until the optical head 3 reaches ~he posit.ion Pl corresponding to the beginning of the area ~. During this narrowing, reciprocating movement of the optical head 3~ any program information data in the output ol the optical head 3 are supplied to thc dec~di..~ circ~i~ry ''- as GU~pUt p~^ogram info~mation da'a S.
The address data at the beginning of the area N are read out when the optical head 3 reaches the position p~.
., 1 Since the output address data L at ~he position Pl match the predetermined address data Lx, the operational signal P from i-the detec,ina meanC q will assume 'he form of a match signal.
The mode control signal Cc from the system controlling means will assume a second form to cause the optical head 3 to establish a playback mode. To begin the playback mode, the optical head 3 performs a one-track-backward jumping operation and enters the area e, where no data are recorded, thereby placing the cptical head 3 at a posltion P2. The position P2 is thus distant from the position Pl by one track and it will take 0.2 -to 0.3 seconds for the optical head 3 to return tc the position Pl from the position P2 when in the playback mode.
After the backward jump by one track of the optical head 3, the mode control signal Cc causes the optical head 3 to operate in the normal playback mode.
The optical head 3, which has been placed at the posiiion P2 and has begun to operate in the playback mode, scans the area e from the position p~ to the position Pl-During the period in which the optical head 3 scans the area e, its output contains substantially no program information data.
The optical head 3 then again enters the area N and reads out the program information data from the beginning thereof.
Meanwhile, as the optical head 3 begins its travel from the posi~ion P2 in the pla~back mode, program information data that was read when the optical head 3 was operating in the searching mode can still be undergoing de-interleaving in the decoding circuitry ]3~ In other words just before a match between the predetermined and output address data is found, the optical head 3 ~ill have provided output program information data to the decoding circuitry 13. When the optical head 3 then begins its playback mode in response to that match, the "residual" undesired program information data, because of the delay inherent in the operation o~ the decoding circuitry 13, is still undergoing de-interleaving. The ma~imum delay, from the time an address data match is found until all residual program information data "clears" the decoder circuitry 13, ~, 11 be the de-lnterleave aelay, in this case about 13.5 msec.
Program information data processed by the decoder circuitry 13 during the searching operation is suppressed by the ~, Q
muting means that controls the operation of the interpolation circuit 14 in response to the mute command signal CM. ~hen an address data match is established, the timer 12 is started by the triggering signal Ts, generated by tlle system controlling means 8 in response to the indication of a match by the match signal.
When the timer set time has run, the overflow signal To from the timer 12 causes the system controlling means 8 to provide the mute release signal CM7 to deactuate the muting means and release the suppression of the interpolating circ~it 14. If the timer set time slightly exceeds the de-interleave delay of 13.5 msec, none of the output program information data, including the residual data, provided ~Jhile the optical head 3 was operating in the searching mode is converted into program information. A
timer set time of 15 msec will establish a suitable muting time if the de-interleave delay is 13.5 msec. Moreover, because the muting of the residual program information data takes place during the operation of the optical head 3 in a clearing period when it is reading the area e of the disc 1 where no data is recorded, the extended muting that ta~es place after a match of predetermined and output address data is established does not inter~ere with the reproduction of the desired program information signal.
FIG. 6 is an alternate embodiment of a disc player according to the present invention. In FIG. 6, ~hose parts corresponding to the parts shown in FIG. 3 are marked with the same references and a further description thereof will be omitted here. In this embodiment a silent-data generating means 17 is provided to produce a silent-data signal SO. The silent-aata signal SO corresponds to prosram information data received from the disc 1 when reading an area containing no program ~2~
informaLion. The silent-data signal SO from the silent-data generating means 17 and the output program information data S are supplied to respective input terminals of a gate means 18. The gate means 18 is controlled by a gate controlling signal CG
supplied from the system controlling means 8 to provide from the gate means 18 either the silent-data signal SO or the output program information data S, depending Gn the gate controlling signal CG, and supply the same to the decoding circultry 13.
The output from the decoding circuitry 13 is supplied to the interpolating circuit 14 to be subjected to error correction by interpolation, as described above. The output frcm the interpolating circuit 14 is supplied to the digital-to-analog converter 15 and a reproduced audio signal representiny the program in~ormation on the disc is obtained at the output of the digital-to-analog converter 15 in the same manner as described in connection with the embodiment shown in FIG. 3. However, when the silent-data signal SO is selected by the gate 18 and supplied to the decoding circuit.y 13 in lieu Gf the outpu8 program information data S, no audio signal is obtained from the digital-to-analog converter 15.
The operation of the embodiment shown in FIG. 6 will be ~, explained in connection with the reproduction of program information data at a specific location X in an area ~, such as that shown in .IG. 2.
As before, the keying signal ~ from the keyboard 10 causes the sy~em controlling means 8 to generate predetermined address data corresponding to that at the speciIic location X in the area N. In response to the keying signal K, the system controlling means 8 provides a first gate controlling sisnal to the gate 18 that causes the gate 18 to provide the silent-data signal SO to the decoding circuitry 13. Simultaneously, the system controlling means 8 also supplies the second register 11 with the predetermined address data Lx correspondiny to the address data at the location X. The first mode control signal is also supplied to the optical head 3 to establish its searching mode whereb~ it will eventually reach the location X by travelling along the path p' as shown in FIG. 2. That is, the optical head 3 repeatedly goes forward and backward over the specific location X a.nd eventually reaches the position Pl' corresponding to the specific location X. During the searching mode o~ the optical heac 3, the silent-data signal SO is supplied to the decoding circuitry 13 in lieu o the output program information data.
When the address data at the location X are read ~y the optical head 3, the output address data L will match the predetermined address data Lx, and the operational signal P
will assume the form of a match signal. The mode control signal CC will zssume its second fGrm and switch the optlcal head 3 to its playback mode, in which the optical head 3 begins reading the program information data at the specific location ~. Further, when the match signal is received by the system controlling means 8, the gaie control signal CG ~7ill assume a second form to cause the gate 1~ to provide to the decoding circuitry 13 the output program information data S received Irom the demodulator 6. The decoded program information data from the decoding circuitry 13 is supplied through ~he interpolating circuit 14 to the digital-to-analog converter 15, and the desired reproduced audio signal is obtained at the output o~ the digital-~o-analog converter 15.
~ 2~7 ~
In this embodiment, the reproduction of undesired program information is avoided by supplying the silent-data signal SO from the silent data generating means 17 to the decoding circuitry 13 in lieu of the output program information data S during the searching operation mode and no program information data read during the searching mode reach the decoding circuitry 13. Accordingly, the desired program information, developed from the program information data read from the specific location X by the optical head 3 operating in its playback mode, can be obtained without any clicking or other spurious sound preceding it.
Of course, the location X can also be set at the beginning of the area N as shown in FIG. 1 and the reproduction of the program information data can be initiated there.
The embodiment shown in FIG. 6 does not require a clearing period where the optical head 3 reads a portion of the disc 1 where there is substantially no program information data while residual, undesired program information dat~ clears ~he decoder circuitry 13, and thus can begin playback~ in the middle o~ an area containing program information data. The embodiment of FIG. 3 is suitable for use when the selec~ed program information is precede~ by an area containing no program information. However, the embodiment of FIG. 6 is suitable for more general application because it can more conveniently begin reproduction at any location on the disc and still suppress undesirable noise caused by the optical head 3 reading prog am information data operating in 'he searching mode.
The present invention has been described with reference to illustrative embodiments, but those skilled in the art will reco~nize that modifications and changes other than any " .
, -17~
~2~7~
specifically pointed out above can be made without departing from the spirit or scope of the present invention. Thus, the scope of the present invention is defined solely by the claims that follow.
. . .
:
S017~9 BAC~GROUN~ OF TIIE INVENTION
Field of the Invention -This invention relates to a method and an apparatus for reproducing program information from a medium in which noise generated by searching for predetermined program information on the medium is suppressed and, more particularly, to a disc player incorporating such a method and apparatus.
Description of the Prior Art In a ~nown recording system a rotatable disc-shaped record medium is used to record digital data representing an audio signal. The digital data are arranged in data blocks that include program information data representing the audio signal, data for error correction, synchronous data and address data. A
disc player is used to reproduce the audio signal from the digital data recorded on the disc. With such a system, very high fidelity reproduction of the audio signal can be obtained.
However, errors in the program information data read by the disc player can affect the reproduced audio signal.
Generally, digital data recorded in any medium inevitably contain data errors caused in the recording process. Such data errors appear infrequently enough that a high Lidelity audio signal can still be obtained Lrom the program information data using error correction techni~ues. Fingerprirts and scratches on the surface or the disc also can cause data errors because they prevent accuxate reading or the program information data recorded on the disc.
Accordingly, recording and reproducing systems using digital data on a disc incorporate a cross-interleave error correction technique for correcting errors that appear in the , , ., -~z~
program inrormation data read from the disc. In recording datausiny a cross-interleave error correction technique, a first error correcting code for a first code arrangement stage and a second error correcting code fox a second code arrangement stage are provided, and then an interleave is carried out between the first and second stages. Using a Reed-Solomon code for the error correcting codes and the interleave technique allows very accurate error correction of the reproduced program information data. However, the corresponding processing circuitry in the disc player for using that error correcting technique requires a finite time, called a de-interleave delay, to convert into program information the program information data read from the disc. That delay causes a problem.
The address data recorded on the disc with the program information data make it possible to reproduce selectively any desired portion of the program information data. The reading device in the disc player is made operative in a searching mode and address data ccnt2ined in the output from _he ~eadin~ deYJice is compared with designated address data associated with the location on the disc of the desired program information. The reading device is operated in the searching mode until the reproduced address data coincide with the designated address data. mhe reading device is then made operative in a playback mode to read the program information data at the location on the disc where the address data match the designated address data.
The output of the reading device in the séarching mode also intermittently contains small amounts of program information data, which is supplied to the processing circuitry and converted into an audio signal after the de-interleave delay time. The audio signal thus obtained appears as a clicking noise or other undesired sound before the selected program information data is reached and converted into the desired program information. The de-interleave delay prevents suppression of that noise merely by preventing conversion of program information data into program information while the reading device is in the searching mode hecause the program information data in the output of the reading device can still be undergoing conversion after the searching mode is terminated.
OBJECTS AND SUI~MAR~ OF THE INV~NTION
~ ccordingly, it is an object of the present invention to provide a method and an apparatus for reproducing program information from a medium that avoids the above described problem encountered in prior art apparatus.
It i5 another object of the present invention to provide for reproducing digital program information data from a disc and suppressing the production of noise caused by operation in a searching mode.
According to an aspect of the present invention r program information is reproduced from a medium containing a plurality of blocks of program information data, each block including address data. During a searching mode, an output is provided containing program informa!ion data and addrcss data used in locating predetermined address data~ The predetermined address data is detected in the output and~ in response to such detection, the medium is read in a playback mode to provide an output comprising program information data for conversion into program information. The conversion into prog,am information of program information data provided during the searching mode is suppressed.
In accordance with one embodiment of the present invention, a clearing period is provided after the playback mode begins when the output contains su~stantially no program information data and the conversion of program information data into program information is suppressed for a predetermined muting time after the predetermined address data is detected, the clearing period being at least as long as the muting time.
In accordance with another embodiment of the present invention, a silent-data slgnal corresponding to program information data containing substantially no program information for converC,ion into program information is generated during the searching mode.
The above and other objects, features and advantages of the present invention will be apparent from the following detailed description tal~en in con~unction with the accompanying drawings.
BRIEF ~ESCRIPTION OF _HE DRAWI~IGS
.
FIG. 1 is an illustration of one type of searching operation that causes the production of undesired audio signals in prior art disc players;
FIG. 2 is an illustration of another type of searching operation that causes the production of undesired audio signals in prior art disc players;
FIG. 3 is a schematic block diagram showing a disc player incorporating a first embodiment of the present invention;
FIG. 4 is a schematic bloc~ diagram showing in detail the operation of the decoding circuitry used in the disc player o F the present lnvention;
FIG. 5 is an illustration of the searching operation performed by the embodiment of the present invention shown in FIG. 3, and FIG. 6 is a schematic block diagram showing a disc player incorporating another embodiment of the present invention.
DETAIL~D DESCRIPTION OF ILLUSTRATIVE E~'~ODIMENTS
FIG. 1 depicts a searching operation that illustrates the problem with spurious search noise encountered in prior art disc players. Assume that the reproduction of program information on a disc is to commence at ~he beginning of a recorded area N in a record track T on the disc. The disc player reading device, operated in its searching mode, moves along the path p in FIG. 1. In doing so the reading device repeatedly goes over areas containing program information data, such as the recorded area N, and areas where no program information data are recorded, such as the area e located between the recorded area N
and a recorded area N-l. The reading device repeatedly moves across the disc until it reaches a position p~ that corresponds to the beginning of the recorded area N.
When the address data provided at the beginning of the recorded area N are read out at the position Pl by the reading device and compared with the designated address data, the disc player determines that the reading device has reached the selected location. Consequently, the reading device is made operative in its playback mode and xeads the program information data in the area N from its beginning.
During the searching mode, and before the desired audio signal is produced from the program information data in the area N provided in the output of the reading device operating in its playbac~: mode, the reading device provides an output containing not only add~ess data but also program information data. During the searching mode, that unwanted program information data are supplied to the decoding circuitry and are converted into an audio signal after the de-interleave delay time (normally about 13.5 msec). The program information data, provided during the searching mode, appears as a clicking noise or other spurious audio signal.
FIG. 2 illustrates the same problem in a case in which the reproduction of program information data is .o be commmenced at a specific location Y~ within a recorded area N. The reading device, operating in its searching mode, moves on the record track T in the path p'. The reading uevice thus repeate~ly yoes over the location X while the amount of movement of the reading device is narrowed down, finally stopping at the location X.
When the address data at the specific location ~ within the recorded area N are read out at the position Pl' by the reading device and compared with the designated address data, the disc player determines that the reading device has reached the selected location. Consequently, t:he reading device is made operative in its playback mode and reads the program information data in the recorded area N, beginning at the location X.
As in the example discussed in ccnnection ~ith FIG. l, be~ore the desired audlo signal is obiained from the program inrormation data in the area ~, the pr~ram in~ormation data provided by the reading device operating in its searching mode are supplied to the decoding circuitry and are converted into an audio signal a~ter the de-interleave delay time. mhus, the same undesirable clicking noise or other spurious sound is p~oduced by the searching operation.
FIG. 3 shows a disc player according to one embodiment of the present invention that overcomes the problem associated with the searching operation depicted in FIG. 1. A disc 1 containing digital program information data accompanied with digital address data is rotated by a motor 2. mhe program information data and the address data recorded on the disc 1 are provided in the OtltpUt of a reading means, which in this embodiment comprises an optical head 3 that directs laser light toward the disc 1 and receives refiected laser l~ght from the disc 1. The reflected light is modulated in response to the data contained on the disc. A photodetector 4 converts the modulated reflected light into an electrical signal containing the program information data and the address data on the disc 1. The electrical signal from the photodetector 4 is shaped by a wa~reform shaping circuit 5 into a suitable digital signal. The digital signal thus obtained is supplied to a demodulator 6 that separates the program in~ormation data and the address data and provides ther;l irl the form o~ output program inrormation data S
and output address data L. The olltpUt address data L are supplied to a Lirst regis~er 7 to be held therein until they are read out in response 'o a control signal CN, supplied from a system controlling means 8, to one input terminal o~ a detecting means 9, as eY.plained below.
A keyboard 10 supplies a keying signal ~ to the system controliing means 8. The ke~rboard 10 comprises a designating means by which an operator can designate ~or playback predetermined program inrorr.ation by causin~ the syster, controlling means 8 to produce predetermined designated address data Lx locating the predetermined program inIormation on the disc in response to the ke~7ing signal ~. The predetermined address data Lx are supplied to a second register 11 to be held therein. The predetermined address data Lx are supplied from the second register 11 to the other input terminal of the detecting means 9. The detecting circuit 9 compares the output address data L with the predetermined a~dress data Lx, which at this time do not match. An operational signal P, obtained as a result of that comparison, is supplied to the system controlling means 8. A mode control signal Cc is supplied to the optical head 3 to establish the searching mode, in which the optical head 3 selectively operates for normal reproduction and for performing a fast-forward operation, a fast-reverse operation, a one-track-forward iumping operation and a one-track-backward iumping operation. The svstem controlling means 8 thus supplies a first mode control signal, effectively in response to the keying signal K, to establish the searching mode of the optical head 3. A timer 12 having a set time of, for example, 15 msec i~
triggered by a timer trigger signal TS provided by the system cont~-olling means ~ when the operational sigrlal P assumes the form of a match signal indicating that the output address data L
coincide with the predetermined address data Lx. In ~esponse to the trigger signal TS the timer 12 provides an over~low signal To to the system controlling means 8 when the set time from the receipt of the triggering signal TS has lapsed.
Meanwhile, the output program information data S from the demodulator 6 are supplied to decoding circuitry ~3 for performing error detection according to the cross-interleave technique, as described in more detail below. The decoded program information data obtained from the decodlng circuitry 13 are supplied to an interpolating circuit 14 in which detected errors are corrected by interpolation. The interpolatinq circuit 14 receives also a mutiny command signal CM and a muting release signal CM' from the system controlling means 8 for selectively actuating and deactuating muting means for suppressing the operation of the interpolating circuit 14 when actuated. The error-corrected, decoded program information data from the interpolating circuit 14 are supplied to a digital-to-analog converter 15 for producing an audio signal representing the progra~ information. The decoding circuitry 13, the interpolating circuit 14 and the digital-to-analog converter 15 thus comprise processing circuit means for eonverting program information da-ta into program information.
FIG. 4 shows in more detail the decoding circuitry 13.
The decoding circuitry 13 comprises a mutliplexer 16A, a first deeoder 16B, a de-interleaver 16C, whieh ineludes a plurality of delay deviees Dl, D2, ete., and a seeond deeoder 16D.
The output program infor~lation data S from the demodulator 6 are supplied to the multiple~er 16A. That data com~rise th~rt~7-twc worac, ~ncluding twenty-fou- audic sign21 data words Sl to S24, four first error~eorreeting words P
to P4 and f~ur seeond error-eorree,ing words Ql to Q4 in each da~a block. The output program information data S thus appear at the output ol the multiplexer 16A as parallel output data. These thirty-two words are supplied to the first decoder 16B. ~n the first decoder 16B~ the first error eorreetion for the data comprising the twenty-four audio signal data words S
to S2~ and the four first error eorreeting words Pl to P4 is carried out by using the four seeond error correcting words Ql to Q4. The first deeoder 16B thus derives data eomprising twenty-four audio signal data words S1' to S24' and rour first eorreeting words P~' to Pal all of which have been _~_ subjected to the first error correction process. At every individual word of the data of these twenty-eight words, a pointer (such as an additional bit) is added to indicate whether there is an error in the associated word or not.
The output data from the first decoder 16B are applied to the de-interleaver 16C which has the delay lines Dl to D28 with respective different delay amounts provided for the twenty eight transmission channels through which the twenty-eight words from the first decoder 16B are respectively transmitted.
With the delay lines Dl to D28, the twenty-eight wcrds from the first decoder 16B are delayed for de-interleaving and twenty-four audio signal data words Sl" to S24" and four first error correcting words Pl" to P4" are derived from the de-interleaver 16C. The sum of the dela~ amounts caused by the delay lines Dl to D28 (the de-interleave delay time) is typically about 13.5 msec. The output from the de-interleaver 16C is then supplied to the second decoder 16D. In the second decodQr 16~, the second error corrQction for the twerty-four audio signal data words Sl" to S24" is carried out by using the four first error correcting words Pl" to P4". The second decoder 16D thus derives twenty-four final audi~ signal data words Fl to F24 that have been subjected to the second error sorrection process and comprise decoded program information data~
At every individual word of these twenty-four words~ a pointer is added to indicate whether or not there is an error in the associated word.
The decoded program information data Fl to F2~ ~hus obtained are supplied to the interpolating circuit 14 for error correction by interpolation for the words having the pointer added thereto. Then, the error-corrected, decoded program 74~
information da-~a are supplied to the digital--o-analog converter 15. The digital-to-analog converter 15 converts the data from the interpolating circuit 14 into an audio signal representing the program information on the disc.
FIG. 5 illustrates the operation OL- the er~odirment of the present invention shown in FIG. 3 in relation to the reproduction o~ program information in a record trac~ ~ on a disc 1 commencing at the beginning of a recorded area N.
First, the keying signal ~, which will be used to eventuall~ position the optical head 3 at the beginning of the recorded area ~, is supplied to the system controlling means ~
from the keyboard 10. In response to the ~eying signal K, the system controlling means 8 provides the muting command signal CM to the interpolating circuit 14 so that the muting means in the interpolatin~ circuit 14 is actuated to block the provision of tne error-corrected, decoded program information data from being supplied to the digital-to-analog converter 15.
Simultaneously, the system controlling means 8 pro~ides the predetermined address data Lx, which corresponds to the address data at the beginning of the recorded area ~, to the second register 11. The mode con~rol signal Cc assumes its first form in which the optical hea~ 3 is placed in the searching mode. The predetermined address data Lx are supplied to the operational circuit 9 from the second register 11 and the output address data L obtained from the photodetector 4 are supplied to the~first register 7 and from there to the operational circuit 9. The operational circuit 9 compares the ou~put address data L with the predetermined address data Lx. When the output address data L
do noi r.latch the designated address data Lx, the mode control signal Cc continues to operate the optical hea~ 3 in its 4~
searching mode. During the searching mode, a comparison between the output address data L and the predetermined address data Lx is performed by the operational circuit 9 whenever address data on the disc 1 are read cut by the optical head 3. The first mode control signal Cc is varied in accordance with the operational signal P obtained in response to the result of that comparison in the opera.ional circuit 9. As a result, the optical head 3 is moved in an optimum fashion until the output address data L match the predetermined address data L . The optical head 3 in the searching mode thus moves in a path p as shown in FTG. 5. That is, in the searching mode, the optical head 3 repeatedly travels forward and backward over recorded areas and areas containing no data and the amount of overshoot of the selected location narrows until the optical head 3 reaches ~he posit.ion Pl corresponding to the beginning of the area ~. During this narrowing, reciprocating movement of the optical head 3~ any program information data in the output ol the optical head 3 are supplied to thc dec~di..~ circ~i~ry ''- as GU~pUt p~^ogram info~mation da'a S.
The address data at the beginning of the area N are read out when the optical head 3 reaches the position p~.
., 1 Since the output address data L at ~he position Pl match the predetermined address data Lx, the operational signal P from i-the detec,ina meanC q will assume 'he form of a match signal.
The mode control signal Cc from the system controlling means will assume a second form to cause the optical head 3 to establish a playback mode. To begin the playback mode, the optical head 3 performs a one-track-backward jumping operation and enters the area e, where no data are recorded, thereby placing the cptical head 3 at a posltion P2. The position P2 is thus distant from the position Pl by one track and it will take 0.2 -to 0.3 seconds for the optical head 3 to return tc the position Pl from the position P2 when in the playback mode.
After the backward jump by one track of the optical head 3, the mode control signal Cc causes the optical head 3 to operate in the normal playback mode.
The optical head 3, which has been placed at the posiiion P2 and has begun to operate in the playback mode, scans the area e from the position p~ to the position Pl-During the period in which the optical head 3 scans the area e, its output contains substantially no program information data.
The optical head 3 then again enters the area N and reads out the program information data from the beginning thereof.
Meanwhile, as the optical head 3 begins its travel from the posi~ion P2 in the pla~back mode, program information data that was read when the optical head 3 was operating in the searching mode can still be undergoing de-interleaving in the decoding circuitry ]3~ In other words just before a match between the predetermined and output address data is found, the optical head 3 ~ill have provided output program information data to the decoding circuitry 13. When the optical head 3 then begins its playback mode in response to that match, the "residual" undesired program information data, because of the delay inherent in the operation o~ the decoding circuitry 13, is still undergoing de-interleaving. The ma~imum delay, from the time an address data match is found until all residual program information data "clears" the decoder circuitry 13, ~, 11 be the de-lnterleave aelay, in this case about 13.5 msec.
Program information data processed by the decoder circuitry 13 during the searching operation is suppressed by the ~, Q
muting means that controls the operation of the interpolation circuit 14 in response to the mute command signal CM. ~hen an address data match is established, the timer 12 is started by the triggering signal Ts, generated by tlle system controlling means 8 in response to the indication of a match by the match signal.
When the timer set time has run, the overflow signal To from the timer 12 causes the system controlling means 8 to provide the mute release signal CM7 to deactuate the muting means and release the suppression of the interpolating circ~it 14. If the timer set time slightly exceeds the de-interleave delay of 13.5 msec, none of the output program information data, including the residual data, provided ~Jhile the optical head 3 was operating in the searching mode is converted into program information. A
timer set time of 15 msec will establish a suitable muting time if the de-interleave delay is 13.5 msec. Moreover, because the muting of the residual program information data takes place during the operation of the optical head 3 in a clearing period when it is reading the area e of the disc 1 where no data is recorded, the extended muting that ta~es place after a match of predetermined and output address data is established does not inter~ere with the reproduction of the desired program information signal.
FIG. 6 is an alternate embodiment of a disc player according to the present invention. In FIG. 6, ~hose parts corresponding to the parts shown in FIG. 3 are marked with the same references and a further description thereof will be omitted here. In this embodiment a silent-data generating means 17 is provided to produce a silent-data signal SO. The silent-aata signal SO corresponds to prosram information data received from the disc 1 when reading an area containing no program ~2~
informaLion. The silent-data signal SO from the silent-data generating means 17 and the output program information data S are supplied to respective input terminals of a gate means 18. The gate means 18 is controlled by a gate controlling signal CG
supplied from the system controlling means 8 to provide from the gate means 18 either the silent-data signal SO or the output program information data S, depending Gn the gate controlling signal CG, and supply the same to the decoding circultry 13.
The output from the decoding circuitry 13 is supplied to the interpolating circuit 14 to be subjected to error correction by interpolation, as described above. The output frcm the interpolating circuit 14 is supplied to the digital-to-analog converter 15 and a reproduced audio signal representiny the program in~ormation on the disc is obtained at the output of the digital-to-analog converter 15 in the same manner as described in connection with the embodiment shown in FIG. 3. However, when the silent-data signal SO is selected by the gate 18 and supplied to the decoding circuit.y 13 in lieu Gf the outpu8 program information data S, no audio signal is obtained from the digital-to-analog converter 15.
The operation of the embodiment shown in FIG. 6 will be ~, explained in connection with the reproduction of program information data at a specific location X in an area ~, such as that shown in .IG. 2.
As before, the keying signal ~ from the keyboard 10 causes the sy~em controlling means 8 to generate predetermined address data corresponding to that at the speciIic location X in the area N. In response to the keying signal K, the system controlling means 8 provides a first gate controlling sisnal to the gate 18 that causes the gate 18 to provide the silent-data signal SO to the decoding circuitry 13. Simultaneously, the system controlling means 8 also supplies the second register 11 with the predetermined address data Lx correspondiny to the address data at the location X. The first mode control signal is also supplied to the optical head 3 to establish its searching mode whereb~ it will eventually reach the location X by travelling along the path p' as shown in FIG. 2. That is, the optical head 3 repeatedly goes forward and backward over the specific location X a.nd eventually reaches the position Pl' corresponding to the specific location X. During the searching mode o~ the optical heac 3, the silent-data signal SO is supplied to the decoding circuitry 13 in lieu o the output program information data.
When the address data at the location X are read ~y the optical head 3, the output address data L will match the predetermined address data Lx, and the operational signal P
will assume the form of a match signal. The mode control signal CC will zssume its second fGrm and switch the optlcal head 3 to its playback mode, in which the optical head 3 begins reading the program information data at the specific location ~. Further, when the match signal is received by the system controlling means 8, the gaie control signal CG ~7ill assume a second form to cause the gate 1~ to provide to the decoding circuitry 13 the output program information data S received Irom the demodulator 6. The decoded program information data from the decoding circuitry 13 is supplied through ~he interpolating circuit 14 to the digital-to-analog converter 15, and the desired reproduced audio signal is obtained at the output o~ the digital-~o-analog converter 15.
~ 2~7 ~
In this embodiment, the reproduction of undesired program information is avoided by supplying the silent-data signal SO from the silent data generating means 17 to the decoding circuitry 13 in lieu of the output program information data S during the searching operation mode and no program information data read during the searching mode reach the decoding circuitry 13. Accordingly, the desired program information, developed from the program information data read from the specific location X by the optical head 3 operating in its playback mode, can be obtained without any clicking or other spurious sound preceding it.
Of course, the location X can also be set at the beginning of the area N as shown in FIG. 1 and the reproduction of the program information data can be initiated there.
The embodiment shown in FIG. 6 does not require a clearing period where the optical head 3 reads a portion of the disc 1 where there is substantially no program information data while residual, undesired program information dat~ clears ~he decoder circuitry 13, and thus can begin playback~ in the middle o~ an area containing program information data. The embodiment of FIG. 3 is suitable for use when the selec~ed program information is precede~ by an area containing no program information. However, the embodiment of FIG. 6 is suitable for more general application because it can more conveniently begin reproduction at any location on the disc and still suppress undesirable noise caused by the optical head 3 reading prog am information data operating in 'he searching mode.
The present invention has been described with reference to illustrative embodiments, but those skilled in the art will reco~nize that modifications and changes other than any " .
, -17~
~2~7~
specifically pointed out above can be made without departing from the spirit or scope of the present invention. Thus, the scope of the present invention is defined solely by the claims that follow.
. . .
:
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A reproducing apparatus for reproducing program information from a medium containing a plurality of blocks of program information data, each block including address data, the apparatus comprising:
reading means for reading the medium and providing an output comprising reproduced program information data and address data, said reading means being selectively operable in a searching mode for locating predetermined address data associated with predetermined program information and a playback mode for providing program information data for conversion into said predetermined program information; said reading means comprising an optical head for reading digital program information data and address data on a substantially planar disc movable relative to said optical head;
processing circuit means for cooperating with said reading means to convert said reproduced program information data into a program information output; said processing circuit means converting said digital program information data into program information corresponding to an audio signal;
detecting means for detecting said address data in said output of said reading means;
system controlling means for controlling said reading means when operating in said searching mode and for establishing said playback mode of said reading means in response to the detection of said predetermined address data by said detecting means; and noise-suppressing means for cooperating with said processing circuit means to suppress the conversion into program information output of reproduced program information data obtained while said reading means is in said searching mode.
reading means for reading the medium and providing an output comprising reproduced program information data and address data, said reading means being selectively operable in a searching mode for locating predetermined address data associated with predetermined program information and a playback mode for providing program information data for conversion into said predetermined program information; said reading means comprising an optical head for reading digital program information data and address data on a substantially planar disc movable relative to said optical head;
processing circuit means for cooperating with said reading means to convert said reproduced program information data into a program information output; said processing circuit means converting said digital program information data into program information corresponding to an audio signal;
detecting means for detecting said address data in said output of said reading means;
system controlling means for controlling said reading means when operating in said searching mode and for establishing said playback mode of said reading means in response to the detection of said predetermined address data by said detecting means; and noise-suppressing means for cooperating with said processing circuit means to suppress the conversion into program information output of reproduced program information data obtained while said reading means is in said searching mode.
2. A reproducing apparatus as in claim 1; wherein:
said noise-suppressing means comprises a selectively actuable muting means for substantially blocking the con-version by said processing circuit means of program informa-tion data into program information while said optical head is in said searching mode and during a predetermined muting time after said predetermined address data is detected; and said system controlling means controls said optical head for providing a predetermined clearing period after said playback mode is established when said program informa-tion data in said output of said optical head is substantial-ly without predetermined program information, said clearing period being at least as long as said muting time.
said noise-suppressing means comprises a selectively actuable muting means for substantially blocking the con-version by said processing circuit means of program informa-tion data into program information while said optical head is in said searching mode and during a predetermined muting time after said predetermined address data is detected; and said system controlling means controls said optical head for providing a predetermined clearing period after said playback mode is established when said program informa-tion data in said output of said optical head is substantial-ly without predetermined program information, said clearing period being at least as long as said muting time.
3. A reproducing apparatus as in claim 2; wherein:
said processing circuit means includes decoding circuitry for accepting said program information data in said output of said optical head and performing a decoding operation thereon to provide at a time later than said acceptance of said program information data by a predeter-mined delay decoded program information data; and said muting time is at least as long as said delay.
said processing circuit means includes decoding circuitry for accepting said program information data in said output of said optical head and performing a decoding operation thereon to provide at a time later than said acceptance of said program information data by a predeter-mined delay decoded program information data; and said muting time is at least as long as said delay.
4. A reproducing apparatus in claim 3; further comprising designatinq means for designating for playback said predetermined program information and for providing a keying signal to said system controlling means and timer means that begin timing when a triggering signal is received from said system controlling means and provides an overflow signal to said system controlling means a set time after receiving said triggering signal, wherein:
said detecting means comprises comparing means for generating a match signal when said address data in said output of said optical head match said predetermined address data; and said system controlling means, in response to said keying signal, provides a muting signal for actuating said muting means, provides to said comparing means said predeter-mined address data and provides a first mode control signal for establishing said searching mode of said optical head and, in response to said match signal, provides said triggering signal to said timer means and provides a second mode control signal for establishing said playback mode of said optical head and, in response to said overflow signal, provides a mute release signal for deactuating said muting means.
said detecting means comprises comparing means for generating a match signal when said address data in said output of said optical head match said predetermined address data; and said system controlling means, in response to said keying signal, provides a muting signal for actuating said muting means, provides to said comparing means said predeter-mined address data and provides a first mode control signal for establishing said searching mode of said optical head and, in response to said match signal, provides said triggering signal to said timer means and provides a second mode control signal for establishing said playback mode of said optical head and, in response to said overflow signal, provides a mute release signal for deactuating said muting means.
5. A reproducing apparatus as in claim 4; wherein said predetermined program information is located on said disc immediately following an area containing no program information and said second mode control signal establishes the beginning of said playback mode in said area to provide said clearing period.
6. A reproducing apparatus as in claim 5; wherein said delay time is about 13.5 msec, said muting time is about 15 msec and said clearing period is between 0.2 and 0.3 seconds.
7. A reproducing apparatus as in claim 4; wherein said processing circuit means includes an interpolating circuit for correcting errors in said decoded program information data, said muting means being operative to suppress the operation of said interpolating circuit, and a digital-to-analog converter for converting said error-corrected, decoded program information data into said program information.
8. A reproducing apparatus as in claim 1; wherein said noise-suppressing means comprises a silent-data gener-ating means for providing a silent-data signal corresponding to program information data substantially without program information to said processing circuit means in lieu of said program information data while said optical head is in said searching mode.
9. A reproducing device as in claim 8; wherein:
said noise-suppressing means further comprises gate means for receiving said silent-data signal and said program information data in said output of said optical head; and said system controlling means provides a gate controlling signal to said gate means for selectively pro-viding to said processing circuit means said silent-data signal and said program information data in said output of said optical head.
said noise-suppressing means further comprises gate means for receiving said silent-data signal and said program information data in said output of said optical head; and said system controlling means provides a gate controlling signal to said gate means for selectively pro-viding to said processing circuit means said silent-data signal and said program information data in said output of said optical head.
10. A reproducing device as in claim 9, further comprising designating means for designating for playback said predetermined program information and for providing a keying signal to said system controlling means, wherein:
said detecting means comprises comparing means for generating a match signal when said address data in said out-put of said optical head match said predetermined address data; and said system controlling means, in response to said keying signal, provides a first gate controlling signal for providing said silent data signal to said processing circuit means, provides to said comparing means said predetermined address data and provides a first mode control signal for establishing said searching mode of said optical head and, in response to said match signal, provides a second gate controlling signal for providing said program information data to said processing circuit means and provides a second mode control signal for establishing said playback mode of said optical head.
said detecting means comprises comparing means for generating a match signal when said address data in said out-put of said optical head match said predetermined address data; and said system controlling means, in response to said keying signal, provides a first gate controlling signal for providing said silent data signal to said processing circuit means, provides to said comparing means said predetermined address data and provides a first mode control signal for establishing said searching mode of said optical head and, in response to said match signal, provides a second gate controlling signal for providing said program information data to said processing circuit means and provides a second mode control signal for establishing said playback mode of said optical head.
11. A reproducing apparatus as in claim 10; wherein said processing circuit means comprises:
decoding circuitry for accepting said program inform-ation data in said output of said optical head and said silent-data signal and performing a decoding operation thereon to provide decoded program information data, an interpolating circuit for accepting said decoded program information data and correcting errors therein; and a digital-to-analog converter for converting said error-corrected, decoded program information data into program information.
decoding circuitry for accepting said program inform-ation data in said output of said optical head and said silent-data signal and performing a decoding operation thereon to provide decoded program information data, an interpolating circuit for accepting said decoded program information data and correcting errors therein; and a digital-to-analog converter for converting said error-corrected, decoded program information data into program information.
12. A method for reproducing program information from a medium containing a plurality of blocks of program informa-tion data, each block including address data, the method comprising:
searching the medium to provide an output comprising program information data and address data for use in locating predetermined address data associated with predetermined program information;
detecting said address data in said output;
halting said searching of the medium in response to detection of said predetermined address data and then reading the medium to provide an output comprising program informa-tion data for conversion into respective program information;
and suppressing the conversion of said program information data into program information during said searching of the medium and thereafter for a predetermined time, at the end of which the converted program information corresponds to said predetermined information data.
searching the medium to provide an output comprising program information data and address data for use in locating predetermined address data associated with predetermined program information;
detecting said address data in said output;
halting said searching of the medium in response to detection of said predetermined address data and then reading the medium to provide an output comprising program informa-tion data for conversion into respective program information;
and suppressing the conversion of said program information data into program information during said searching of the medium and thereafter for a predetermined time, at the end of which the converted program information corresponds to said predetermined information data.
13. A method as in claim 12; further comprising the steps of:
decoding program information data supplied during said searching and reading to provide decoded program in-formation data at a predetermined delay time after said decoding begins, said predetermined time being at least as long as said delay; and providing a predetermined clearing period after the reading of said medium begins when said program information data in said output of said reading means is substantially without predetermined program information, said clearing period being at least as long as said predetermined time.
decoding program information data supplied during said searching and reading to provide decoded program in-formation data at a predetermined delay time after said decoding begins, said predetermined time being at least as long as said delay; and providing a predetermined clearing period after the reading of said medium begins when said program information data in said output of said reading means is substantially without predetermined program information, said clearing period being at least as long as said predetermined time.
14. A method as in claim 13; wherein:
said searching step comprises the sub-step of design-ating said predetermined address data to initiate said searching step;
said detecting step comprises the sub-steps of comparing said designated address data with the address data in said output and generating a match signal when said designated address data match said address data in said output;
said reading step is initiated in response to said match signal; and said suppressing step comprises the sub-steps of measuring the elapsed time from said match signal and generating a mute release signal for permitting conversion of program information data in said output into program information a set time after the generation of said match signal.
said searching step comprises the sub-step of design-ating said predetermined address data to initiate said searching step;
said detecting step comprises the sub-steps of comparing said designated address data with the address data in said output and generating a match signal when said designated address data match said address data in said output;
said reading step is initiated in response to said match signal; and said suppressing step comprises the sub-steps of measuring the elapsed time from said match signal and generating a mute release signal for permitting conversion of program information data in said output into program information a set time after the generation of said match signal.
15. A method as in claim 14, further comprising the steps of:
interpolating said decoded program information data to provide error-corrected, decoded program information data, wherein said suppressing step blocks the provision of said error-corrected, decoded program information data and converting said error-corrected, decoded program.
information data into program information representing an audio signal.
interpolating said decoded program information data to provide error-corrected, decoded program information data, wherein said suppressing step blocks the provision of said error-corrected, decoded program information data and converting said error-corrected, decoded program.
information data into program information representing an audio signal.
16. A method as in claim 14; wherein said reading step is initiated in an area of the medium containing no program information for providing said clearing period.
17. A method for reproducing program information from a medium containing a plurality of blocks of program informa-tion data, each block including address data, the method comprising:
searching the medium to provide an output comprising program information data and address data for use in locating predetermined address data associated with predetermined program information;
detecting said predetermined address data in said output;
reading the medium in response to detection of said predetermined address data to provide an output comprising program information data for conversion into said predeter-mined program information; and generating a silent-data signal corresponding to program information data substantially without program information for conversion into program information during said searching step.
searching the medium to provide an output comprising program information data and address data for use in locating predetermined address data associated with predetermined program information;
detecting said predetermined address data in said output;
reading the medium in response to detection of said predetermined address data to provide an output comprising program information data for conversion into said predeter-mined program information; and generating a silent-data signal corresponding to program information data substantially without program information for conversion into program information during said searching step.
18. A method as in claim 17; wherein said reading step comprises the sub-step of initiating the conversion into program information of program information data from the medium in response to detection of said predetermined address data.
19. A method as in claim 17; further comprising the steps of:
decoding program information data supplied during said searching and reading steps to provide decoded program information data;
interpolating said decoded program information data to provide error-corrected, decoded program information data;
and converting said error-corrected, decoded program information data into program information representing an audio signal. 27
decoding program information data supplied during said searching and reading steps to provide decoded program information data;
interpolating said decoded program information data to provide error-corrected, decoded program information data;
and converting said error-corrected, decoded program information data into program information representing an audio signal. 27
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8715782A JPS58203608A (en) | 1982-05-23 | 1982-05-23 | Disk reproducing device |
| JP87157/82 | 1982-05-23 | ||
| JP88445/82 | 1982-05-25 | ||
| JP8844582A JPS58205914A (en) | 1982-05-25 | 1982-05-25 | Disc reproducer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1207440A true CA1207440A (en) | 1986-07-08 |
Family
ID=26428461
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000428697A Expired CA1207440A (en) | 1982-05-23 | 1983-05-24 | Disc player with search noise suppression |
Country Status (6)
| Country | Link |
|---|---|
| US (2) | US4592036A (en) |
| KR (1) | KR920000213B1 (en) |
| CA (1) | CA1207440A (en) |
| DE (1) | DE3318497C2 (en) |
| FR (1) | FR2527369B1 (en) |
| GB (2) | GB2123596B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61193581A (en) * | 1985-02-21 | 1986-08-28 | Fuji Photo Film Co Ltd | Synchronizing control for image signal reproducing device |
| EP0232134B1 (en) * | 1986-02-07 | 1994-08-24 | Matsushita Electric Industrial Co., Ltd. | Optical disc and disc drive apparatus for writing/reading data into/from the disc |
| US5173886A (en) * | 1986-02-07 | 1992-12-22 | Matsushita Electric Industrial Co., Ltd. | Composite optical disc having both a data read-only area and a data rewritable area, and a recording/reproducing system for use therewith |
| JPH0772971B2 (en) * | 1988-10-05 | 1995-08-02 | パイオニア株式会社 | Disc player playback level setting method |
| JPH0636469A (en) * | 1992-06-16 | 1994-02-10 | Sony Corp | Recording medium and recording method for recording medium |
| US6442329B1 (en) * | 1998-02-28 | 2002-08-27 | Michael L. Gough | Method and apparatus for traversing a multiplexed data packet stream |
| JP4373021B2 (en) * | 2001-02-27 | 2009-11-25 | 株式会社日立グローバルストレージテクノロジーズ | Information recording / reproducing device |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1531214A (en) * | 1974-11-18 | 1978-11-08 | Rca Corp | Squelch circuit |
| GB1577133A (en) * | 1976-03-19 | 1980-10-22 | Rca Corp | Video information record and playback apparatus |
| FR2349191A1 (en) * | 1976-04-23 | 1977-11-18 | Thomson Brandt | OPTICAL INFORMATION DISC READER INCLUDING AN AUTOMATIC INFORMATION ACCESS DEVICE |
| JPS53142208A (en) * | 1977-05-18 | 1978-12-11 | Teac Corp | Method of recording pcm signal |
| GB1603828A (en) * | 1977-05-24 | 1981-12-02 | Rediffusion Reditronics Ltd | Tape record and playback systems |
| US4246615A (en) * | 1977-12-16 | 1981-01-20 | Victor Company Of Japan, Limited | System for recording and/or reproducing an audio signal which has been converted into a digital signal |
| GB2032677B (en) * | 1978-10-04 | 1982-08-11 | Dewey T | Sound reproduction devices |
| US4321635A (en) * | 1979-04-20 | 1982-03-23 | Teac Corporation | Apparatus for selective retrieval of information streams or items |
| JPS5624885A (en) | 1979-08-06 | 1981-03-10 | Matsushita Electric Ind Co Ltd | Audio muting circuit |
| US4286290A (en) * | 1979-08-20 | 1981-08-25 | Rca Corporation | Fast recovery squelch circuit for a video disc player |
| JPS6125108Y2 (en) * | 1980-07-29 | 1986-07-28 | ||
| JPS5736479A (en) * | 1980-07-29 | 1982-02-27 | Victor Co Of Japan Ltd | Automatic program searching playback device in playback device |
| US4361849A (en) * | 1980-11-06 | 1982-11-30 | Rca Corporation | Video disc vari-speed playback system |
| JPS57148975U (en) * | 1981-03-12 | 1982-09-18 | ||
| JPS57181430A (en) * | 1981-04-30 | 1982-11-08 | Sony Corp | Dad player |
| JPS57198586A (en) * | 1981-05-28 | 1982-12-06 | Sony Corp | Digital disc reproducing device |
| US4484174A (en) * | 1982-01-07 | 1984-11-20 | Rca Corporation | Video disc player having improved squelch system |
| JPS5938912A (en) * | 1982-08-27 | 1984-03-03 | Nec Corp | Pcm audio error compensating circuit |
-
1983
- 1983-05-20 FR FR8308410A patent/FR2527369B1/en not_active Expired
- 1983-05-20 GB GB08314047A patent/GB2123596B/en not_active Expired
- 1983-05-20 DE DE3318497A patent/DE3318497C2/en not_active Expired - Lifetime
- 1983-05-23 KR KR1019830002250A patent/KR920000213B1/en not_active IP Right Cessation
- 1983-05-23 US US06/497,404 patent/US4592036A/en not_active Expired - Lifetime
- 1983-05-24 CA CA000428697A patent/CA1207440A/en not_active Expired
-
1985
- 1985-05-16 GB GB08512415A patent/GB2157878B/en not_active Expired
-
1986
- 1986-03-06 US US06/837,028 patent/US4682312A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| GB8512415D0 (en) | 1985-06-19 |
| KR840004970A (en) | 1984-10-31 |
| FR2527369A1 (en) | 1983-11-25 |
| GB8314047D0 (en) | 1983-06-29 |
| GB2157878B (en) | 1986-04-16 |
| US4682312A (en) | 1987-07-21 |
| DE3318497C2 (en) | 1994-03-10 |
| DE3318497A1 (en) | 1983-12-15 |
| KR920000213B1 (en) | 1992-01-10 |
| FR2527369B1 (en) | 1987-04-17 |
| US4592036A (en) | 1986-05-27 |
| GB2123596B (en) | 1986-04-16 |
| GB2123596A (en) | 1984-02-01 |
| GB2157878A (en) | 1985-10-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |